Electro-Slag Remelting Installation

ABSTRACT

An electro-slag remelting installation includes a mold and a consumable electrode that extends into the mold. The consumable electrode has an axis that is oriented obliquely to a vertical axis.

This application claims the priority of International Application No. PCT/DE2016/100339, filed Jul. 26, 2016, and German Patent Application No. 10 2015 117 661.0, filed Oct. 16, 2015, and German Patent Application No. 10 2015 112 229.4, filed Jul. 27, 2015, the entire disclosures of which are herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to an electro-slag remelting installation with a mold, which is open at the top, and at least one consumable electrode, which extends into the mold.

Such an installation is described in DE 198 39 432 C2 for example.

To produce an ingot (block) out of impurities-free metal, the end of the consumable electrode that extends into the mold is melted off. The melted metal falls through a liquid slag above a molten material in the mold, wherein a chemical reaction of the metal with the slag removes these impurities, such as sulfur and other non-metallic elements, from the metal. Inclusions in the electrode are thus transferred to the slag and do not reach the block.

The temperature required to melt the consumable electrode is generated by a high-ampere electric current, which flows through the consumable electrode, the slag, and the molten material. The slag thereby represents an electrical resistor, which heats up due to the current passing through. The slag is thereby liquefied and heated. The two electrical poles of the slag form, on the one hand, the block building up in the mold, and on the other hand, the electrode. Due to the heat generated in the slag, the electrode melts at the interface to the slag.

The higher the temperature of the slag, the higher is the melting rate of the electrode. However, limits are set for the temperature level of the slag. For that reason, the melting rate can only be increased by increasing the cross-sectional area while keeping the slag bath temperature constant.

In the known design of such an installation, the consumable electrode is a rod-shaped structure with a round or rectangular cross-section, whose axis has a vertical orientation. The melting rate thereby depends on the cross-sectional area in relation to a plane perpendicular to the axis of the electrode. In the past, the diameter of the mold and the diameter of the electrode had been increased to achieve higher melting rates. However, the mold diameter also determines the size of the blocks that are produced from the solidified molten material. In order to also achieve a sufficiently high melting rate for small block sizes, so-called funnel molds (funnels) are utilized. In the upper, funnel-shaped sections of the mold, there is immersed the consumable electrode, whose cross-section is larger than the cross-section of the lower, smaller section of the funnel mold, which holds the block.

Therefore, the object of the invention consists of creating an electro-slag remelting installation, which has an increased melting rate despite a small given cross-section of the consumable electrode.

To solve the task, the invention provides that the consumable electrode is oriented obliquely to a vertical.

The end surface of the consumable electrode extending into the mold thereby runs, corresponding to its inclination, obliquely to the axis of the consumable electrode.

Therefore, the effective consumable surface no longer corresponds to the cross-sectional area in relation to a plane perpendicular to the axis of the electrode, but in relation to a horizontal plane. The effective consumable surface thus increases by the inverse of the cosine of the angle between the vertical and the axis of the obliquely positioned consumable electrode.

Besides increasing the consumable surface, this arrangement also has additional advantages.

In the past, to obtain larger consumable surfaces, a plurality of electrodes were welded together to obtain a thicker electrode. This step is now no longer necessary.

Since the electrode is arranged obliquely, the overall height of the installation is decreased or given the same overall height, longer consumable electrodes can be used.

The oblique arrangement enables one to have available one or more electrodes near the later melt-off position to thereby minimize the time delay when changing electrodes.

Preferably, the angle between the axis of the consumable electrode and the vertical is between 20 and 60°; in particular, it is 450°.

As the electrode undergoes melting loss, it must be re-fed. To this end, the invention provides that the consumable electrode is held in a refeeding unit that is designed in such a manner that the consumable electrode can be displaced along its obliquely positioned axis.

Such a refeeding unit may have a roller bearing. In this way, the weight of the consumable electrode can be distributed over multiple rollers.

As done in installations according to prior art, at least two consumable electrodes can also be provided here, which are each furnished with a refeeding unit. This allows for a rapid exchange of electrodes. An electrode is being melted off, while the other is being prepared in its displacement system and is displaced into a position above the mold as soon as the preceding one is consumed.

As mentioned above, the mold is cooled so that the molten material solidifies in its lower region and can be removed as a billet from the open bottom of the mold. To do so, a device is provided that extracts molten material, whose lower section has solidified into a billet, through the bottom of the mold.

If small-sized blocks are to be formed in this way, a separating apparatus can still be provided, which is designed in such a manner that it can separate the end piece of the billet emerging from the bottom of the mold. In addition, a deflection device may be provided, which diverts the separated end pieces laterally to the mold, e.g., on to a conveyor belt, into a warehouse or storage facility.

The invention is to be explained in greater detail below by means of an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the arrangement; and

FIG. 2 is a top view.

DETAILED DESCRIPTION OF THE DRAWINGS

The installation according to the invention consists of a mold 1, which consists of a tube body 2 having the same cross-section and a funnel 3 connecting on the top. Plunging into it is a consumable electrode 4, whose axis 5 is arranged obliquely to a vertical 6, which simultaneously forms the axis of tube body 2. Consumable electrode 4 is seated on rollers 7, which form an oblique plane. Consumable electrode 4 is held by a refeeding unit 8, by means of which it can be refed into funnel 3 of mold 1 commensurate to the melt-off.

The tube body 2 contains the molten material that forms and that solidifies due to the cooling, not depicted here, in the lower region into a billet 10, which is removed downwardly by an apparatus not depicted here and which, if applicable, may be divided into individual blocks by a separating device also not depicted here. These are diverted by a deflection apparatus, which is also not depicted in greater detail, in a lateral direction via means, e.g., a conveyor belt, into a warehouse or storage facility (not depicted).

Above molten material 9, there is within funnel 3 a slag layer 11 with a horizontally running surface, which is contacted by consumable electrode 4.

The melting rate level is determined by the size of the consumable surface 13, which is the end surface of consumable electrode 4 contacting slag layer 11. Consumable surface 13 runs horizontally and thus, depending on the inclination of consumable electrode 4, oblique to its axis 5. Since consumable electrode 4 is positioned obliquely, consumable surface 13 increases in relation to cross-sectional area 12 of consumable electrode 4 by an amount that is determined by the size of angle α between axis 5 of consumable electrode 4 and vertical 6. For an angle of 45°, end surface 13 increases by approx. 40% compared to cross-sectional area 12.

To allow for an oblique infeed of consumable electrode 4, funnel 3 has an oblique infeed edge 14 on the side of consumable electrode 4.

The energy for consuming electrode 4 is obtained from a power supply not depicted here. Consumable electrode 4, slag layer 11 as well as molten material 9 and billet 10 form parts of a current circuit, wherein slag layer 11 represents the largest resistance so that most of the energy is absorbed there.

LIST OF REFERENCE SIGNS

-   -   1 Mold     -   2 Tube body     -   3 Funnel     -   4 Consumable electrode     -   5 Axis     -   6 Vertical     -   7 Rollers     -   8 Refeeding unit     -   9 Molten material     -   10 Billet     -   11 Slag layer     -   12 Cross-sectional area     -   13 End surface     -   14 Infeed edge 

1.-9. (canceled)
 10. An electro-slag remelting installation, comprising: a mold, wherein the mold is open on a top of the mold; and a consumable electrode, wherein the consumable electrode extends into the mold and wherein the consumable electrode has an axis that is oriented obliquely to a vertical axis.
 11. The electro-slag remelting installation according to claim 10, wherein an end surface of the consumable electrode that extends into the mold runs obliquely to the axis of the consumable electrode.
 12. The electro-slag remelting installation according to claim 10, wherein an angle between the axis of the consumable electrode and the vertical axis is between 20° and 60°.
 13. The electro-slag remelting installation according to claim 10 further comprising a refeeding unit, wherein the consumable electrode is held in the refeeding unit such that the consumable electrode is displaceable along the axis of the consumable electrode.
 14. The electro-slag remelting installation according to claim 13 further comprising a second consumable electrode and a second refeeding unit, wherein the second consumable electrode is held in the second refeeding unit such that the second consumable electrode is displaceable along an axis of the second consumable electrode.
 15. The electro-slag remelting installation according to claim 13 further comprising a displacement system, wherein the refeeding unit with the consumable electrode is movable over the mold by the displacement system.
 16. The electro-slag remelting installation according to claim 10 further comprising a device that removes molten material, which has solidified into a billet in a bottom section of the mold, through a bottom of the mold.
 17. The electro-slag remelting installation according to claim 16 further comprising a separation apparatus that separates an end piece of the billet emerging from the bottom of the mold.
 18. The electro-slag remelting installation according to claim 17 further comprising a deflection apparatus that diverts the separated end piece in a lateral direction with respect to the mold. 